Controlling of exposure for an individual person in a facility where radioactive radiation is handled must include a daily control (control of exposure throughout a day), a weekly control (control of exposure throughout a week) and a monthly control (control of exposure throughout a month). It is accepted practice to carry out daily control and weekly control relying upon the records of everyday dosage using a conventional pocket intensitometer or a TLD (thermal luminescence detector). As for the monthly control, the person carries the TLD and a film badge with him for a month, and the dosage is controlled relying upon the readings. As described above, the exposure to the individual persons has been controlled by recording and totalizing the exposure data of daily control.
According to the above-mentioned prior art, however, no attention has been given to controlling the exposure based upon the history of exposure of the individual persons, and the totalized data after the exposure is often left unnoticed though it may have exceeded the control value.
In controlling the exposure for an individual person, furthermore, it is necessary to record and preserve the history of dosage to which he is exposed. The careful control of exposure during the work in the radioactive radiation is carried out based upon the history of dosage to which the person is exposed. However, the conventional intensitometer does not have a function for stably recording for extended periods of time the history of dosage to which the person is exposed.